Spray cylinder

Abstract

 A rotating spray cylinder (12) for use in tobacco processing is provided with a plurality of retractable pins (14). Cam surface (16) acts on a cam follower (22) on each pin to cause an extendable portion (20) of each pin to extend into the cylinder during upward movement of the pin on the cylinder to help convey material in the cylinder. The pins retract from the cylinder during downward movement to remove material adhered to the pin. A scraper (50) scrapes the interior cylinder surface while the pins are retracted.

Description

[0001] This invention relates to spray cylinders, and more particularly to spray cylinders for use with the processing of tobacco or similar materials.

[0002] Stationary pins positioned on the inside walls of spray cylinders are currently used in conveying and mixing tobacco or other similar materials during rotation of the cylinder for such purposes as blending, steam-conditioning, drying, and applying flavorants. Highly-saturated clumps of tobacco or other similar materials tend to accumulate on or around these stationary pins. The clumps may not be dried to desired moisture levels, and remain saturated. Those clumps which subsequently fall into the tobacco or other similar materials within the cylinder disturb the uniform moisture level and flavorant concentration of the tobacco or other similar materials. In the case of tobacco, this can result in spotting on cigarettes. Additionally, those clumps which do not fall remain adhered to the stationary pins, spray rack, and inside wall of the cylinder. These clumps must be disposed of, resulting in waste of starting material. It is desirable to convey the tobacco or other similar materials during rotation of the cylinder in such a way that uniform moisture and flavorant concentrations are achieved without the accumulation of material into clumps.

[0003] The present invention aims to provide an improved spray cylinder and accordingly provides a rotating spray cylinder for use in the processing of tobacco or other similar materials placed within the cylinder, the cylinder comprising a plurality of pins mounted on the wall of the cylinder, characterised in that the pins are retractable, and further characterised by means for alternatively extending and retracting the pins into and out of the interior of the cylinder on rotation thereof.

[0004] The invention also provides a method of conveying and mixing tobacco or other similar materials in a hollow spray cylinder having a substantially horizontal central longitudinal axis and a plurality of longitudinal pins mounted on said cylinder so that the longitudinal axis of each pin is substantially radial of said cylinder, said pins being spaced from one another about the circumference of said cylinder, the method comprising rotating said cylinder about its central longitudinal axis and being characterised by extending a longitudinal portion of each pin parallel to its longitudinal axis into the interior of the cylinder for at least a portion of the period of rotation of the cylinder, and by subsequently withdrawing the longitudinal portion of each pin from the interior of said cylinder.

[0005] A preferred embodiment of the invention provides retractable, self-cleaning pins mounted on the wall of the rotating cylinder. These retractable pins extend into the cylinder during the upward portion of rotation when they are needed to convey the material, and retract out during the downward portion when they are not needed.

[0006] Embodiments of the invention will now be described with reference to the accompanying drawings in which:

[0007] FIG.1 is a simplified cross-sectional view of an illustrative embodiment of a spray cylinder embodying the invention.

[0008] FIG 2 is a longitudinal view, partly in section, of a retractable, self-cleaning pin of the apparatus shown in FIG. 1.

[0009] FIG 3 is a view similar to FIG. 1 showing an alternative illustrative embodiment of the invention.

[0010] Although the principles of this invention are applicable to blend, steam-condition, dry, or add flavorants to materials such as tobacco, the invention will be fully understood from the following explanation of an illustrative embodiment in the context of cylinders used for applying a spray to strip tobacco.

[0011] As shown in FIG. 1, a preferred embodiment of a retractable pin system 10 of this invention includes cylinder 12, retractable pins 14, and cam 16. The central longitudinal axis of cylinder 12 is typically horizontal or somewhat inclined and is therefore sometimes referred to herein as "substantially horizontal." System 10 includes a plurality of retractable pins 14 which are preferably positioned on the outer surface of cylinder 12. These pins may be distributed in any fashion about the circumference and length of cylinder 12. Each retractable pin 14 is preferably mounted substantially normal to the surface of cylinder 12 (i.e., substantially radially of the cylinder) and over an associated opening in the cylinder wall. A portion of each retractable pin 14, indicated by reference number 20, is extendable through the opening in cylinder 12 in which the retractable pin 14 is mounted. Another portion of each retractable pin 14, in particular cam follower 22, is designed to come into contact with, and move along cam 16.

[0012] During operation of the apparatus, cylinder 12 rotates about its longitudinal axis, as shown by arrow 18. As the rotation of cylinder 12 brings the cam follower 22 of each retractable pin 14 into contact with cam 16, portion 20 of that retractable pin 14 extends into the cylinder. Once the rotation of cylinder 12 moves a given retractable pin 14 away from cam 16, portion 20 of that pin is retracted from the inside of the cylinder by an associated prestressed compression spring 26 (see FIG. 2). Compression spring 26 is located within the cylindrical housing 24 or each retractable pin 14. During retraction, material which may have adhered to portion 20 is removed or scraped from portion 20 by a lip seal 28 (e.g., of metal such as stainless steel or carbon steel or any other suitable material) located where retractable pin 14 passes through bushing 30. In a preferred embodiment of the invention, portion 20 of each retractable pin 14 is extended into cylinder 12 during the generally upward movement of that pin in order to help convey the material within cylinder 12. Portion 20 of each retractable pin 14 is retracted from the inside of cylinder 12 during the generally downward movement of that pin allowing the material being conveyed within cylinder 12 to fall freely.

[0013] FIG. 2 shows a preferred embodiment of a retractable pin 14 in greater detail. In its relaxed position retractable pin 14 is held retracted from the inside of cylinder 12 by compression spring 26 located in spring cavity 32 inside cylindrical housing 24. The inner end of spring 26 bears on bushing 30 (which is effectively an extension of the wall of cylinder 12), and the outer end of spring 26 bears on collar 40, which travels with extendable portion 20, and which rests against bushing 38 during the relaxation state of spring 26. Spring 26 coils around extendable portion 20, which is typically round in cross section. As cam follower 22, which may be a roller bearing held in place by a mounting bracket 36, comes into contact with cam 16, extendable portion 20 is pushed into the interior of cylinder 12. Portion 34 of retractable pin 14 is disposed outside cylindrical housing 24 during the relaxation state of spring 26, and is preferably noncircular (e.g., square) in cross section so as to prevent rotation of mounting bracket 36. Once the rotation of cylinder 12 moves cam follower 22 away from cam 16, compression spring 26 returns to its relaxation state and causes extended portion 20 to retract from the inside of cylinder 12.

[0014] Because pins 14 are withdrawn from the interior of cylinder 12 in one circumferential region of the cylinder, a stationary scraper 50 (FIG. 3) can (if desired) be mounted so that it extends axially through the cylinder and scrapes the wall of the cylinder as it passes through that circumferential region. Pins 14 and scraper 50 do not interfere with one another because pins 14 are withdrawn from the interior of cylinder 12 as the pins pass the scraper. If provided, scraper 50 helps prevent the adherence of any portion of the material being processed to the inner surface of cylinder 12.

[0015] It will be understood that the foregoing is merely illustrative of the principles of this invention, and that various modifications can be made by those skilled in the art
For example, although spring 26 is located between bushing 30 and collar 40 in the depicted embodiment, it could alternatively be located between bracket 36 and bushing 38 (although in that event it would not be protected by housing 24 as in the depicted preferred embodiment). As another alternative, compression spring 26 could be replaced by a prestressed tension spring connected at one end to bushing 38 and at the other end to a part of extendable portion 20 which always remains inside housing 24. As still another example of possible modifications within the scope of this invention, although in the depicted embodiment spring 26 resiliently biases pin 20 outwardly of cylinder 12 and cam 16 pushes the pin into the cylinder, the spring (e.g., a tension spring in place of compression spring 26) could be used to resiliently bias the pin into the cylinder, while the cam (e.g., a cam disposed between cylinder 12 and bracket 36) is used to pull the pin out of the cylinder. Electrical, electromagnetic, or pneumatic means could also be used to control the radial positions of the pins. As yet another example, although the retractable pins are uniformly distributed around the circumference of the cylinder in FIG. 1, it will be readily apparent that the apparatus can be modified so that the retractable pins are nonuniformly distributed about the circumference and length of the cylinder.

Claims

1. A rotating spray cylinder for use in the processing of tobacco or other similar materials placed within the cylinder (12) the cylinder comprising a plurality of pins (14) mounted on the wall of the cylinder, characterised in that the pins are retractable, and further characterised by means (16) for alternatively extending and retracting the pins into and out of the interior of the cylinder on rotation thereof.

2. A cylinder according to claim 1, characterised in that the pin extending and retracting means extends a given pin into the interior of the cylinder during generally upward movement of the pin relative to the axis of rotation of the cylinder and retracts the pin from the cylinder interior during generally downward movement of the pin.

3. A cylinder according to claim 1 or 2, characterised in that each pin has an extendable portion (20) which extends into the interior of the cylinder when the means for alternately extending and retracting extends the pin, and a non-extendable portion (24) which remains outside the cylinder at all times, and in that the means for alternately extending and retracting the pins comprises for each pin a prestressed spring captured between the wall of the cylinder and a part (40) of the non-extendable portion of the pin, and a cam follower (22) attached to the non-extendable portion of the pins, and for the plurality of pins, a cam (16) disposed outside a portion of the circumference of the cylinder for contact by the cam follower to extend the pins into the interior of the cylinder.

4. A cylinder according to claim 3, characterised in that the cam follower is a roller bearing.

5. A cylinder according to any of claims 1 to 4, characterised in that each pin has an extendable portion (20) which extends into the interior of the cylinder when the means for alternately extending and retracting extends the pin, and a non-extendable (24) portion which remains outside the cylinder at all times, further comprising means (28) for surrounding and scraping the extended portion of each pin when the pin is retracted.

6. A cylinder according to any preceding claim, characterised by means (50) for scraping the interior surface of the cylinder where the pins are retracted from the interior of the cylinder.

7. The method of conveying and mixing tobacco or other similar materials in a hollow spray cylinder having (1) a substantially horizontal central longitudinal axis and (2) a plurality of longitudinal pins mounted on said cylinder so that the longitudinal axis of each pin is substantially radial of said cylinder, said pins being spaced from one another about the circumference of said cylinder, the method comprising rotating said cylinder about its central longitudinal axis and being characterised by extending a longitudinal portion of each pin parallel to its longitudinal axis into the interior of the cylinder for at least a portion of the period of rotation of the cylinder, and subsequently withdrawing the longitudinal portion of each pin from the interior of said cylinder.

8. The method defined in claim 7, characterised by withdrawing each pin during at least a portion of the time that the portion of the cylinder on which said pin is mounted is moving downward due to the rotation of said cylinder.

9. The method defined in claim 7 and 8, characterised by extending each pin during at least a portion of the time that the portion of the cylinder on which the pin is mounted is moving upwards due to rotation of the cylinder.

10. The method defined in claim 7, 8 or 9 characterised by scraping the surface of the longitudinal portion of each pin to remove any tobacco or other similar materials while withdrawing the pin.

11. The method defined in claim 7, 8, 9 or 10 characterised by scraping the interior surface of the cylinder where the pins are withdrawn.

Drawing